Infinite Loop with While inside Foreach and MySQL

Question

I'm having a very odd problem with PHP/MySQL...

echos "id;id"

 foreach($ids as $id) {
      echo "id;";
 }

echos "id;id;id;id;..." (infinite loop)

 foreach($ids as $id) {
      while($row = mysqli_fetch_array(mysqli_query($conn, "SELECT * FROM `Table` WHERE `id`=$id;") {
           echo "id;";
      }
 }

The reason I have a foreach() statement is because I have $ids sorted.

Answer 1

You will get an infinite loop, simply because you run the query anew every single time through the while loop. That means, for each $id , you continuously run the query and extract the first row from it. So, for any query that returns more than zero rows, the continual re-execution of that query will make the while loop endless.

It's functionally similar in effect to the following pseudo-code, which will also loop forever since you're modifying the control condition within the loop:

loop i from 1 to 10
    set i to 1
endloop

You should instead try something like:

foreach($ids as $id) {
    $result = mysqli_query($conn, "SELECT * FROM `Table` WHERE `id`=$id;");
    while($row = mysqli_fetch_array($result)) {
       echo "id;";
    }
}

This will run the query once for each ID and the while loop will process the rows for that query.